Dedicated to Prof. Dr S. Ebel on his 70th birthday1 The functional characterization of hispidulin (4 0 ,5,7-trihydroxy-6-methoxyflavone), a potent benzodiazepine (BZD) receptor ligand, was initiated to determine its potential as a modulator of central nervous system activity. 2 After chemical synthesis, hispidulin was investigated at recombinant GABA A /BZD receptors expressed by Xenopus laevis oocytes. Concentrations of 50 nM and higher stimulated the GABAinduced chloride currents at tested receptor subtypes (a 1À3,5,6 b 2 g 2 S) indicating positive allosteric properties. Maximal stimulation at a 1 b 2 g 2 S was observed with 10 mM hispidulin. In contrast to diazepam, hispidulin modulated the a 6 b 2 g 2 S-GABA A receptor subtype.3 When fed to seizure-prone Mongolian gerbils (Meriones unguiculatus) in a model of epilepsy, hispidulin (10 mg kg À1 body weight (BW) per day) and diazepam (2 mg kg À1 BW per day) markedly reduced the number of animals suffering from seizures after 7 days of treatment (30 and 25% of animals in the respective treatment groups, vs 80% in the vehicle group). 4 Permeability across the blood-brain barrier for the chemically synthesized, 14 C-labelled hispidulin was confirmed by a rat in situ perfusion model. With an uptake rate (K in ) of 1.14 ml min À1 g À1 , measurements approached the values obtained with highly penetrating compounds such as diazepam. 5 Experiments with Caco-2 cells predict that orally administered hispidulin enters circulation in its intact form. At a concentration of 30 mM, the flavone crossed the monolayer without degradation as verified by the absence of glucuronidated metabolites.
Acrylamide, used in the manufacture of polyacrylamide and grouting agents, is also present in the diet and tobacco smoke. It is a neurotoxin and a probable human carcinogen. Analytical methods were established to determine the mercapturic acids of acrylamide (N-acetyl-S-(2-carbamoylethyl)-L-cysteine, AAMA) and its metabolite glycidamide (N-(R/S)-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine, GAMA) by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS), as well as the N-terminal valine adduct of acrylamide (N-2-carbamoylethylvaline, AAVal) released by N-alkyl Edman degradation of hemoglobin by gas chromatography-mass spectrometry (GC-MS). Twenty-four-hour urine samples from 60 smokers and 60 nonsmokers were analyzed for AAMA and GAMA, and blood samples were analyzed for AAVal. Smokers excreted 2.5-fold higher amounts of AAMA and 1.7-fold higher amounts of GAMA in their urine and had 3-fold higher levels of AAVal in their blood. All three biomarkers of acrylamide exposure were strongly correlated with the smoking dose as determined by the daily cigarette consumption, nicotine equivalents (the molar sum of nicotine, cotinine, trans-3'-hydroxycotinine, and their respective glucuronides) in urine, salivary cotinine, and carbon monoxide in expired breath. In nonsmokers, a weak but significant correlation between AAMA and the estimated dietary intake of acrylamide was found. It is concluded that all three biomarkers of acrylamide are suitable for the determination of exposure in both smokers and nonsmokers.
Benzodiazepine receptor binding assay-guided fractionation of the methanol extract from sage leaves ( Salvia officinalis L.) revealed three flavones and two abietane diterpenes functioning as benzodiazepine receptor-active components. Structural elucidation of the isolated pure compounds was performed by UV, EI-MS, ESI(pos)-MS/MS, as well as 1H- and 13C-NMR techniques. The flavones apigenin, hispidulin and cirsimaritin competitively inhibited 3H-flumazenil binding to the benzodiazepine receptor with IC50 values of 30, 1.3 and 350 microM, respectively. In addition, the affinities of the newly discovered diterpene receptor ligands, i. e., 7-methoxyrosmanol and galdosol, were characterized. 7-Methoxyrosmanol exhibited an IC50 value of 7.2 microM and galdosol showed the strongest binding activity to the benzodiazepine receptor with an IC50 value of 0.8 microM.
Tobacco-specific N-nitrosamines (TSNA) include 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N'-nitrosonornicotine (NNN), N'-nitrosoanabasine (NAB) and N'-nitrosoanatabine (NAT) and are found in tobacco and tobacco smoke. TSNA are of interest for biomonitoring of tobacco-smoke exposure as they are associated with carcinogenesis. Both NNK and NNN are classified by IARC as Group 1 carcinogens. Samples of 24 h urine collections (n = 108) were analysed from smokers and non-smokers, using a newly developed and validated LC-MS/MS method for determining total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL, the major metabolite of NNK), and total NNN, NAB and NAT. TSNA levels in smokers' urine were significantly higher than in non-smokers. In smokers, urinary excretion of total TSNA correlated significantly (r > 0.5) with markers of smoking dose, such as daily cigarette consumption, salivary cotinine and urinary nicotine equivalents and increased with the ISO tar yield of cigarettes smoked. The correlation between urinary total NNN and the smoking dose was weaker (r = 0.4-0.5). In conclusion, this new method is suitable for assessing tobacco use-related exposure to NNK, NNN, NAB and NAT.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.